1. How did the Ming Dynasty display its dominance with vassal states like Korea and Southeast Asia?

Korea and may other states in Asia had a tributary relationship with imperial China. Their rulers were supposed to send annual tributes - gold, jewels, animals, etc. - to the Chinese emperor. China was the center of the Asian system, the highest civilization of all and its ruler was superior to anybody else, the Son of Heaven did not have equals. It was the practice during the Ming dynasty and later.